Cationic sizing agent and its solubilization with a cationic quaternary compound



United States Patent 3,268,470 CATIONIC SIZING AGENT AND ITS SOLUBILIZA- HON WITH A CATJIONIC QUATERNARY COM- POUND Edward Helmut Sheers, Flushing, N.Y., and David Randal Sexsmith, Norwalk, Conm, assignors to American Cyanamid Company, Stamford, Conn., a corporation of Maine No Drawing. Filed Oct. 2, 1963, Ser. No. 313,197 5 Claims. (Cl. 260-29.6)

This is a continuation-in-part of our copending application Serial No. 69,276, filed on November 15, 1960, now abandoned.

The present invention relates to the dissolving of cationic sizing :agents in aqueous media. The invention includes blends of cationic sizing agents with quaternary ammonium agents which improve the solubility of these sizing agents and methods for dissolving the sizing agents in aqueous media by use of these quaternary ammonium agents.

Cationic sizing agents are hydrophobic waxy substances which when dispersed in water are substantive to cellulose fibers and render them resistant to penetration by aqueous fluids. They are therefore valuable as beater additives in the manufacture of paper.

Cationic sizing agents generally have softening points in excess of 90100 C. They are insoluble in cold water and are diflicult to dissolve in hot water. Satisfactory solutions have been prepared by dissolving the sizing agents in a water-soluble organic solvent therefor and then mixing the resulting solutions with water, but this entails a substantial expense for the organic solvent. Attempts to improve the solubility of the sizes in cold Water by grinding have not been successful because when the sizes are ground sufficiently fine to increase their surface area to a useful extent, the particles tend to clump together. Even when boiling water is used, they always dissolve slowly and frequently incompletely.

The cationic sizes generally form clear solutions in water, but some form cloudy colloidal or semi-colloidal suspensions. For convenience the term solution is generally used to designate the suspensions as well, and the term solubilization to the procedures involved in preparing the solutions and the dispersions.

The discovery has now been made that the cationic sizing agents dissolve readily in cold (i.e., 20 C.) water when the water contains a small amount of a watersoluble higher alkyl cationic quaternary ammonium compound as water solubilizing agent. The term higher alkyl means that the compounds contain at least one alkyl substituent of at least 12 carbon atoms. In preferred instances only a few percent of the quaternary ammonium compound is needed, and the sizes disperse rapidly and completely in such water without need for the steps described above.

The cationic higher alkyl quaternary ammonium compounds are powerful wetting agents and are substantively absorbed by cellulose papermaking fibers as completely as are the cationic sizes themselves. It is therefore surprising that these compounds do not exert any significant adverse effect upon the water-resistance imparted by the size even when employed in amounts as high as of the weight of the size. Laboratory data suggest that the cationic size masks or otherwise cancels the hydrophilic (wetting) properties possessed by the quaternary ammonium compounds. The real explanation, however, has not as yet been ascertained, and we do not wish to be bound by any theory.

One preferred embodiment of the invention is a dry blend consisting essentially of the cationic sizing agent and a small but effective amount of the quaternary am- "ice monium compound as Water-solubilizing agent therefor. In such blend, the sizing agent and the quaternary ammonium compound constitute discrete entities, and the quaternary ammonium compound is not dissolved in the size.

This blend dissolves rapidly and completely when stirred into the minimum amount of water at 20 C. needed to form a fluid solution. The resulting soapy opalescent molecular or colloidal dispersion of the size can then be diluted to any desired degree by addition of water, hot or cold, and the product added to papermaking beater stock.

A second embodiment of the invention resides in dissolving an effective amount of the quaternary ammonium compound in water, and then stirring in the size to form a similar dispersion.

The amount of the quaternary compound present in any one instance of the present invention depends chiefly upon the specific ecectiveness of the agent, the hydrophobicity of the cationic size, the temperature of the water, and the sizezwater ratio. A suitable amount may readily be determined by laboratory trial as shown in the examples. As a rule of thumb, in preferred instances we have found it satisfactory to employ between 1% and 5% of cationic agent based on the weight of the size and a sizezwater ratio of 1:5 to 1:25. We have further found that the temperature of the water may be as low as 20 C. and need not be in excess of 55 C.

The invention does not depend on the pH of the water to form the initial dispersion, and we have obtained satisfactory results at pH value from 3 to 12.

Water-soluble higher alkyl cationic quaternary ammonium compounds suitable for use in the present invention include those shown in the examples below, together with polymeric compounds such as polymerized Z-(diethylamino)ethyl acrylate quaternized with octadecyl bromide, polymerized p-chloromethylstyrene quaternized with dimethyloctadecylamine, and polymerized N-methylethylenimine quaternized with oca-tdecylbromide.

The cationic sizes are organic compounds, which are both hydrophobic and hydrophilic in nature. They are sutficiently hydrophobic so that when melted and cast as a film they shed water without being wet. On the other hand, they are sufliciently hydrophilic so that the molecular or colloidal dispersions thereof in water are stable. They are cationic as shown by electrophoresis and contain at least one basic amino or quaternary ammonium group per molecule. Their molecular weight may be in the monomeric and polymeric ranges. They may be quickly recognized by forming a solution thereof in an organic solvent, adding the solution to water and employing the resulting solution or dispersion as a beater additive to cellulose stock at pH 7-9. Substantive adsorption of the material in question by the fibers with development of paper having resistance to penetration by water when the fibers are sheeted and dried, shows that the material is a size.

Preferably the concentration of quaternary ammonium solubilizing agent in the water in which the size is dispersed is between 0.05% and 0.5% by weight.

The present invention benefits both monomeric and polymeric sizes.

The monomeric sizes benefited include the higher fatty acid amines, e.g. octadecylamine, and the higher alkyl amide-amine soap group of sizes. A preferred example of the latter sizes is prepared by reacting 1 mol of diethylenetriamine with 1.8 mol of stearic acid at an amidation temperature until 1.4 mol of Water has evolved, acidifying the molten product with 1 mol of glacial acetic acid, and rapidly cooling to room temperature.

Another substantially monomeric cationic-size can be prepared by refluxing 1 mol of hexahydro-l,3,5-triacrylyl- Hydrophilic cationic linkages include The polymers may contain minor amounts of nonfunctional diluent or spacing units, such as, for example,

CH CH (CONH CH CH( OH) and CH CH(OOCCH linkages.

The polymeric sizes benefited by the invention can be prepared, for example, by subjecting a mixture of styrene and dimethylaminoethyl methacrylate to vinyl polymerization, and quaternizing the product with benzyl chloride.

The polymers benefited by the invention are substantially insoluble in cold water, i.e., they dissolve in water at 20 C. when coarsely ground to the extent of less than 5% in 5 minutes and therefore require more than about 100 minutes for complete solution.

The invention will be more particularly illustrated by the examples which follow, which constitute specific embodiments of the invention and are not to be construed as limitations thereon.

Example I The following illustrates the solubilizing effect of various amounts of a higher alkyl quaternary ammonium compound upon a coarsely-ground cationic size, and the efiect on the sizing of the quaternary ammonium compound in the paper.

The size is prepared by copolymerizing a 1:1 molar ratio mixture of vinyl stearate and vinyl chloroacetate, stirring 79 g. (1 mol) of pyridine into 431 g. of the copolymer at 40-S0 C. and reacting the mixture at 90 C. for one-half hour. The resulting quaternized copolymer is cooled to room temperature and the resulting hard waxy material is broken down to about mesh particle size in a mortar and pestle.

The efiiectiveness of the higher alkyl quaternary ammoni um compound is illustrated by dry blending 10 g.

' of the resulting size with the amounts shown in the table below of powdered N-octadecyl pyridinium chloride and manually stirring the blend into 200 cc. of water having the temperatures shown below. Results are as follows:

Percent Solubilization of Size in Percent Qnater. Cpd. ater at Run No. Size in on Weight ot Size Water 55 C. 20 G.

Control (1) 5. 0 O 0 Incomplete Incomplete. 2 5. 0 1 0. 05 do Do. 3-- 5. 0 2 0. 1 Slow but Do.

complete. 4 5. 0 5 O. 25 Rapid and Slow but complete. complete. 5 0 10 0.5 do Rapid and complete.

The products of runs 3, 4, and 5 are hazy solutions having a soapy feel and the viscosity of Water.

The sizing results afforded by the above-described solutions are determined by standard laboratory method wherein aliquots are removed from an aqueous suspension of southern kratt pulp having a consistency of 0.6%, a pH of 7.0 and a temperature of 20 C., a suflicient quantity of the solutions is added to the aliquots to provide 0.5% of size based on the dry weight of the fibers therein, handsheets are formed from the aliquots, the handsheets are dried at 240 F. for three minutes, and the water absorption of the handsheets is determined after they have been totally immersed in water at 73 F. for

15 minutes. Results are as follows:

Run No. Percent; Quat. Sheet Basis Percent H 0 Cpd. Added 1 Wt. Absorbed 3 Control (1) None 240 39. 9 3 2 240 39. 8 5 243 40. 1 10 236 41. 2

1 Polymer solids on dry weight of fibers. 2 Lb. per 25"X40"/50O ream. 3 Adjusted to 2401b. basis weight.

The results show that the quaternary ammonium compound had negligible etfect upon the water resistance imparted by the size.

Example 2 pound as shown in the table below, and the resulting blends are manually stirred into 500 cc. of water having a pH of? and a temperature of C.

Solubilization is rated on a scale wherein 0 designates no dissolution or dispersion of the polymer, and 10 designates rapid and complete dissolution or dispersion thereof. On this scale a value of 3 is about the minimum result which would be commercially acceptable, and 8 represents very satisfactory solubilization of the size. Results are as follows:

Rate of No. Dispersing Agent Solubiliz.

of Size 1 N-octadecylpyridinium chloride 10 2 Octadecyl trimethyl ammonium chloride 9 3 Hexadecyl trimethyl ammonium chloride 8 4 Hexadecylpyridinium chloride 8 5 Tallow trimethyl ammonium chloride 6 6 Dodeeyl trimethyl ammonium chloride. 5 7 Octasdeiylamidopropyl dimethyl ammonium 5 in re e. 8 Dioctadecyl dimethyl ammonium chloride 2+ 9 Polymerized chloromethylstyrene fully quater- 2+ nized with trimethylamine.

1 Prepared by method of Example 1 of Jen et :11. Application Serial Example 3 The following illustrates the effect of the higher alkyl cationic quaternary ammonium compound upon the solubility of the size of Example 1 in coarse form in comparison with the solubility of the size in very finelydivided form.

The coarse size is prepared by breaking up a cast sheet of size in a mortar and pestle to about 10 mesh.

The finely-divided size is prepared by drum-cooling the molten size to a film thickness of about 1 mil and then micropulverizing the film. The product is a dust of platelets about 1 mil thick and about 10 microns in diameter. The higher alkyl quaternary ammonium compound is powdered N-octadecyl pyridinium chloride.

The method of Example 1 is followed for dissolving the samples. Results are as follows at the end of three The results show that the coarsely ground size in admixture with a small amount of higher alkyl dispersing agent disperses in Water better than the size which has been ground to near-colloidal dimensions.

Example 4 The following illustrates the solubilization of the coarsely ground size of Example 1 as a function of the percent of higher alkyl quaternary ammonium compound present in the aqueous phase. In each run 10 g. of the size is stirred into water at 55 C. and pH 7.0 containing N- octadecyl pyridinium chloride; the amounts of water and of the quaternary ammonium compound are shown in the table below. Results are as follows:

Amt. Quaternary Run H20, Cpd. Present N 0. cc. solubilization of Size Gm. Percent 1 Percent 2 1 500 0 0 Insoluble. 2 500 O. 0. 01 0. 05 Incomplete. 3 500 0. 1 0.02 0. 1 Slow but complete. 4 500 0. 2 0. O4 0. 2 Faster and complete. 5 50 0. 1 0. 2 O. 1 Slow and complete. 6 50 0.2 0. 4 0. 2 Rapid and complete.

l On weight of water.

2 On weight of size.

Comparison of run 3 with run 5 and comparison of run 4 with run 6 show that it is best to disperse the size in a small amount of water so as to maintain a comparatively high concentration of the quaternary ammonium compound in the aqueous phase until dispersion of the size is complete.

Example 5 The following illustrates additional solubilizations of cationic sizes according to the present invention. In each instance 20 g. of coarsely ground size shown in the table below in admixture with 1.0 g. of octadecyl pyridinium chloride as the quaternary ammonium compound is manually stirred into 100 cc. of water at pH 7 and 55 C. Results are as follows at the end of three minutes of stirring and are shown in comparison with the results obtained without use of the quaternary ammonium compound.

Prepared by method of Example 1 01' Ten et al. application serial No. 742,496, filed on June 17, 1958.

2 Prepared according to the general method of Example 5 of Daniel application serial No. 548,773, filed on November 23, 1955, now U.S. Patent No. 2,964,445 of December 13, 1060.

3 The polymer is substantially composed of CHQCH(OOCIBHQ7) and -C]:Iz-CH[OOC-CH N(OH linkages.

Example 6 The solubilization of monomeric cationic sizing agents is illustrated as follows:

Size A.This size is prepared by heating 1 mol of tetraethylenepentamine with 2.8 mols of stearic acid at 200 C. for a few minutes with stirring, cooling the mixture to 115 C., stirring in 1 mol of glacial acetic acid, and rapidly cooling the mixture to room temperature. A hard wax is obtained which is coarsely ground.

Size B.This size is octadecylamine hydrochloride, coarsely ground.

These sizes do not dissolve substantially when stirred with 99 parts of Water at 20 C. for 100 minutes.

The sizes dissolve in a few minutes when stirred with 99 parts of water at 20 C. containing 1% by weight of dodecyl trimethyl ammonium chloride.

We claim:

1. A dry blend consisting essentially of a normally solid normally cold water-insoluble cationic paper sizing agent containing at least one basic amino or quaternary ammonium group per molecule and a small but eifective amount of a water-soluble cationic quaternary ammonium compound containing at least one alkyl substituent of at least 12 carbon atoms as water-solubilizing agent therefor.

2. A composition according to claim 1 wherein the quaternary ammonium compound is N-octadecyl. pyridinium chloride.

3. A composition according to claim 1 wherein the quaternary ammonium compound is octadecyl trimethyl ammonium chloride.

4. A composition according to claim 1 wherein the sizing agent has a particle size in the range of about10 to 50 mesh.

5. A dry blend consisting essentially of a normally solid normally cold water-insoluble vinyl copolymeric cationic paper sizing agent substantially composed of and CH -CH[OOCCH N(CH linkages in about 1:1 molar ratio and a small but effective amount of N octadecylpyridinium chloride as Water solubilizing agent therefor.

References Cited by the Examiner UNITED STATES PATENTS 2,848,413 8/1958 Schuller 252 -8.8 3,001,957 9/1961 Kray 117-155 3,048,539 9/1962 Kocay et al 252-8.8 3,050,506 8/1962 Sexsmith 26029,6

MURRAY TILLMAN, Primary Examiner.

P. LIEBERMAN, Assistant Examiner. 

1. A DRY BLEND CONSISTING ESSENTIALLY OF A NORMALLY SOLID NORMALLY COLD WATER-INSOLUBLE CATIONIC PAPER SIZING AGENT CONTAINING AT LEAST ONE BASIC AMINO OR QUANTERNARY AMMONIUM GROUP PER MOLECULE AND A SMALL BUT EFFECTIVE AMOUNT OF A WATER-SOLUBLE CATIONIC QUATERNARY AMMONIUM COMPOUND CONTAINING AT LEAST ONE ALKYL SUBSTITUENT AT A LEAST 12 CARBON ATOMS AS WATER-SOLUBILIZNG AGENT THEREFOR. 